{"id":"CVE-2026-47121","aliases":["GHSA-hg88-v3cw-3qrh"],"url":"https://o3.security/vulnerability/CVE-2026-47121","summary":"Sparkle: Binary delta apply intermediate-symlink traversal in malicious .delta","details":"Sparkle is a software update framework for macOS. Prior to version 2.9.2, `Autoupdate/SUBinaryDeltaApply.m` enforces `relativePath.pathComponents containsObject:@\"..\"` and rejects writes whose immediate parent directory IS itself a symbolic link, but does not detect symlinks deeper in the relative path. `Autoupdate/SPUSparkleDeltaArchive.m`'s `extractItem:` will create symlinks in the destination tree from archive content (no `..` check on the symlink target), and a subsequent `Extract` item targeting `<symlink>/foo/bar` then escapes the destination tree via `fopen(path, \"wb\")` because the kernel resolves the intermediate symlink during the open call. This is a defense-in-depth issue: exploitation requires a maliciously-crafted `.delta` that passes EdDSA signature verification, i.e. EdDSA private-key compromise. With the AppInstaller running as root for system-domain installs, it gives the holder of a stolen signing key arbitrary file write at root level via the delta-apply path, which is a strictly broader primitive than the \"drop-in replacement bundle\" install they would otherwise have. Version 2.9.2 contains a patch for the issue.","published":"2026-07-21T13:53:05.030Z","modified":"2026-08-12T03:51:40.509660485Z","cvss":{"score":6.1,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N"},"epss":{"score":0.00229,"percentile":0.13955,"asOf":"2026-08-20"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"SwiftURL","name":"github.com/sparkle-project/Sparkle","fixedVersion":"2.9.2"}],"fix":{"url":"https://github.com/sparkle-project/Sparkle/commit/fe7b718d0736f3e139e374e26fbca96f29e13bf0","label":"sparkle-project/Sparkle@fe7b718"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47121.json"},{"type":"ADVISORY","url":"https://github.com/sparkle-project/Sparkle/security/advisories/GHSA-hg88-v3cw-3qrh"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-47121"},{"type":"FIX","url":"https://github.com/sparkle-project/Sparkle/commit/fe7b718d0736f3e139e374e26fbca96f29e13bf0"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:40.509660485Z"}}